It is common in many military and commercial applications to have electronic enclosures for storing a number of electronic components, particularly commercial off the shelf (“COTS”) devices. These electronic enclosures may be in the form of a console, a cabinet, a rack, etc., depending on the types of COTS devices being stored and the environment where the electronic enclosures are located. Typical electronic enclosures are also connected to a power source for supplying power to the electronic components stored by the enclosure.
A typical problem associated with electronic components such as COTS devices and electronic enclosures are leakage currents that result in potential shock hazards. A leakage current is defined as any current that conducts along exposed conductive surfaces and through the protective ground conductor of an electronic component or enclosure. Leakage currents are typically generated by filtering components and parasitic elements within an electronic component that circulate a current back to the power source via ground. COTS devices are typically required to adhere to Underwriters Laboratories (“UL”) leakage current limits of 3.5 mA. Similarly, electronic enclosures that store electronic components are typically required to adhere to leakage current limits of 3.5-21 mA, depending on the enclosure being used. A problem associated with storing a number of COTS devices in an electronic enclosure is that the leakage currents produced by the individual devices are accumulated by the electronic enclosure, thereby generating a high enclosure leakage current that is above the specified limits.
Conventionally, several methods have been used to reduce leakage currents in electronic enclosures. One method is to select electronic components that generate less leakage current or limit the number of electronic components stored in the electronic enclosure. However, there may be limited options when choosing one electronic component over another, and simply reducing the number of electronic components stored in each enclosure results in requiring more enclosures. Another method is to power an enclosure and the electronic components therein using multiple cables connecting the enclosure to the power source. This allows the user to distribute generated leakage current amongst the different circuits. However, providing more power cables to the enclosure merely transfers the leakage current risks from the enclosure to the power source powering the enclosure. Yet another method is to use an isolation transformer to provide a high impedance element in the leakage current loop path. However, isolation transformers contribute significant weight and take up a significant amount of space in the electronic enclosures. Also, the use of an isolation transformer in an electronic enclosure increases the costs of the enclosure as well.
Accordingly, there is a need for improved devices and methods for successfully reducing leakage currents that is low weight, takes limited space, and is inexpensive without simply shifting leakage current risks to another location.